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Frédéric Cappa - One of the best experts on this subject based on the ideXlab platform.
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Seismic Velocity changes associated with aSeismic deformations of a fault stimulated by fluid injection
Geophysical Research Letters, 2016Co-Authors: Diane Rive, Frédéric Cappa, Louis De Barros, Yves Guglielmi, R Castilla, Pierre HenryAbstract:Fluid pressure plays an important role in the stability of tectonic faults. However, the in situ mechanical response of faults to fluid-pressure variations is still poorly known. To address this question, we performed a fluid-injection experiment in a fault zone in shales while monitoring fault movements at the injection source and Seismic Velocity variations from a near-distance (<10 meters) monitoring network. We measured and located the P- and S-wave Velocity perturbations in and around the fault using repetitive active sources. We observed that Seismic Velocity perturbations dramatically increase above 1.5 MPa of injection pressure. This is consistent with an increase of fluid flow associated with an aSeismic dilatant shearing of the fault as shown by numerical modelling. We find that Seismic Velocity changes are sensitive both to fault opening by fluid invasion and effective stress variations, and can be an efficient measurement for monitoring fluid-driven aSeismic deformations of faults.
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Seismic Velocity changes associated with aSeismic deformations of a fault stimulated by fluid injection
Geophysical Research Letters, 2016Co-Authors: Diane Rivet, Frédéric Cappa, Louis De Barros, Yves Guglielmi, R Castilla, Pierre HenryAbstract:Fluid pressure plays an important role in the stability of tectonic faults. However, the in situ mechanical response of faults to fluid-pressure variations is still poorly known. To address this question, we performed a fluid-injection experiment in a fault zone in shales while monitoring fault movements at the injection source and Seismic Velocity variations from a near-distance (
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Improved detection of preeruptive Seismic Velocity drops at the Piton de La Fournaise volcano, Geophysical Research Letters, vol. 42, n°15, pp. 6332-6339, 2015.
Geophysical Research Letters, 2015Co-Authors: Florent Brenguier, Diane Rivet, Frédéric CappaAbstract:The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of Seismic velocities of the Piton de la Fournaise volcano inferred from Seismic noise correlations have been shown to precede eruptions. However, Seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory Seismic Velocity changes to an eruption by removing the effects of pore pressure changes. During 2011–2013, the volcano exhibits a low eruptive activity during which we observe Seismic Velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and Seismic Velocity changes. We use these results to correct Seismic Velocity change time series for pore pressure changes, due to rainfall and found a preeruptive Velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.
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Improved detection of preeruptive Seismic Velocity drops at the Piton de La Fournaise volcano: PREERUPTIVE Seismic Velocity DROPS
Geophysical Research Letters, 2015Co-Authors: Diane Rivet, Florent Brenguier, Frédéric CappaAbstract:The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of Seismic velocities of the Piton de la Fournaise volcano inferred from Seismic noise correlations have been shown to precede eruptions. However, Seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory Seismic Velocity changes to an eruption by removing the effects of pore pressure changes. During 2011–2013, the volcano exhibits a low eruptive activity during which we observe Seismic Velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and Seismic Velocity changes. We use these results to correct Seismic Velocity change time series for pore pressure changes, due to rainfall and found a preeruptive Velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.
Florent Brenguier - One of the best experts on this subject based on the ideXlab platform.
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Retrieving robust noise-based Seismic Velocity changes from sparse data sets: synthetic tests and application to Klyuchevskoy volcanic group (Kamchatka)
Geophysical Journal International, 2018Co-Authors: C Gómez-garcía, N M Shapiro, Florent Brenguier, P. Boue, D Droznin, S. Ya. Droznina, S. L. Senyukov, E. I. GordeevAbstract:Continuous noise-based monitoring of Seismic Velocity changes provides insights into volcanic unrest, earthquake mechanisms and fluid injection in the subsurface. The standard monitoring approach relies on measuring traveltime changes of late coda arrivals between daily and reference noise cross-correlations, usually chosen as stacks of daily cross-correlations. The main assumption of this method is that the shape of the noise correlations does not change over time or, in other terms, that the ambient-noise sources are stationary through time. These conditions are not fulfilled when a strong episodic source of noise, such as a volcanic tremor, for example, perturbs the reconstructed Green's function. In this paper, we propose a general formulation for retrieving continuous time-series of noise-based Seismic Velocity changes without the requirement of any arbitrary reference cross-correlation function (CCF). Instead, we measure the changes between all possible pairs of daily cross-correlations and invert them using different smoothing parameters to obtain the final Velocity change curve. We perform synthetic tests in order to establish a general framework for future applications of this technique. In particular, we study the reliability of Velocity change measurements versus the stability of noise CCFs. We apply this approach to a complex data set of noise cross-correlations at Klyuchevskoy volcanic group (Kamchatka), hampered by loss of data and the presence of highly non-stationary Seismic tremors.
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Seasonal Crustal Seismic Velocity Changes Throughout Japan
Journal of Geophysical Research: Solid Earth, 2017Co-Authors: Qing-yu Wang, Michel Campillo, Florent Brenguier, Albanne Lecointre, Tetsuya Takeda, Yosuke AokiAbstract:Noise-based crustal Seismic Velocity changes are known to be affected by environmental perturbations, such as rainfall, atmospheric pressure loading, and temperature changes. Similar to geodetic observations, these external perturbations can mask the effects of tectonic and volcanic processes. In this study, we benefit from the dense Hi-net short-period Seismic network that covers the entire Japan to measure continuous changes in Seismic velocities over a few years, using noise-based Seismic monitoring. Some strong seasonal Seismic Velocity changes are observed in both southern Japan (Kyushu Island) and northern Japan (Hokkaido Island). Decreasing of Seismic velocities in summer in southern Japan can be clearly explained by a model of increased crustal fluid pore pressure associated with high rainfall. In northern Japan, it is necessary to adopt a more complex model to explain the observed Seismic Velocity variations, which takes into account precipitation, snow depth, and sea level changes. Moreover, western and eastern Hokkaido Island show very different responses to these different external perturbations. The models developed are used to remove the seasonal components of the Seismic Velocity changes. The minimum remaining detectable Seismic Velocity change reduces to 10−5, which allows detection of crustal responses to small earthquakes that are previously hidden in the strong seasonal perturbations.
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Investigation of coSeismic and postSeismic processes using in situ measurements of Seismic Velocity variations in an underground mine
Geophysical Research Letters, 2015Co-Authors: Gerrit Olivier, Michel Campillo, N M Shapiro, Florent Brenguier, Philippe Roux, Richard LynchAbstract:The in situ mechanical response of a rock mass to a sudden dynamic and static stress change is still poorly known. To tackle this question, we conducted an experiment in an underground mine to examine (1) the influence of dynamic and static stress perturbations on Seismic velocities, (2) elastic static stress changes, and (3) induced earthquake activity associated with the blast and removal of a portion of hard rock. We accurately (0.01%) measured Seismic Velocity variations with ambient Seismic noise correlations, located aftershock activity, and performed elastic static stress modeling. Overall, we observe that the blast induced a sudden decrease in Seismic velocities over the entire studied area, which we interpreted as the damage due to the passing of strong Seismic waves. This sudden process is followed by a slow relaxation lasting up to 5 days, while Seismic activity returns to its background level after 2 days. In some locations, after the short-term effects of the blast have subsided, the Seismic velocities converge to new baseline levels and permanent changes in Seismic Velocity become visible. After comparing the spatial pattern of permanent Seismic Velocity changes with elastic static stress modeling, we infer that the permanent Seismic Velocity changes are due to the change in the static volumetric stress induced by the removal of a solid portion of rock by the blast. To our knowledge, this is the first observation of noise-based permanent Seismic Velocity changes associated with static stress changes.
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Improved detection of preeruptive Seismic Velocity drops at the Piton de La Fournaise volcano, Geophysical Research Letters, vol. 42, n°15, pp. 6332-6339, 2015.
Geophysical Research Letters, 2015Co-Authors: Florent Brenguier, Diane Rivet, Frédéric CappaAbstract:The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of Seismic velocities of the Piton de la Fournaise volcano inferred from Seismic noise correlations have been shown to precede eruptions. However, Seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory Seismic Velocity changes to an eruption by removing the effects of pore pressure changes. During 2011–2013, the volcano exhibits a low eruptive activity during which we observe Seismic Velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and Seismic Velocity changes. We use these results to correct Seismic Velocity change time series for pore pressure changes, due to rainfall and found a preeruptive Velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.
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Improved detection of preeruptive Seismic Velocity drops at the Piton de La Fournaise volcano: PREERUPTIVE Seismic Velocity DROPS
Geophysical Research Letters, 2015Co-Authors: Diane Rivet, Florent Brenguier, Frédéric CappaAbstract:The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of Seismic velocities of the Piton de la Fournaise volcano inferred from Seismic noise correlations have been shown to precede eruptions. However, Seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory Seismic Velocity changes to an eruption by removing the effects of pore pressure changes. During 2011–2013, the volcano exhibits a low eruptive activity during which we observe Seismic Velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and Seismic Velocity changes. We use these results to correct Seismic Velocity change time series for pore pressure changes, due to rainfall and found a preeruptive Velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.
Diane Rivet - One of the best experts on this subject based on the ideXlab platform.
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Seismic Velocity changes associated with aSeismic deformations of a fault stimulated by fluid injection
Geophysical Research Letters, 2016Co-Authors: Diane Rivet, Frédéric Cappa, Louis De Barros, Yves Guglielmi, R Castilla, Pierre HenryAbstract:Fluid pressure plays an important role in the stability of tectonic faults. However, the in situ mechanical response of faults to fluid-pressure variations is still poorly known. To address this question, we performed a fluid-injection experiment in a fault zone in shales while monitoring fault movements at the injection source and Seismic Velocity variations from a near-distance (
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Improved detection of preeruptive Seismic Velocity drops at the Piton de La Fournaise volcano, Geophysical Research Letters, vol. 42, n°15, pp. 6332-6339, 2015.
Geophysical Research Letters, 2015Co-Authors: Florent Brenguier, Diane Rivet, Frédéric CappaAbstract:The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of Seismic velocities of the Piton de la Fournaise volcano inferred from Seismic noise correlations have been shown to precede eruptions. However, Seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory Seismic Velocity changes to an eruption by removing the effects of pore pressure changes. During 2011–2013, the volcano exhibits a low eruptive activity during which we observe Seismic Velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and Seismic Velocity changes. We use these results to correct Seismic Velocity change time series for pore pressure changes, due to rainfall and found a preeruptive Velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.
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Improved detection of preeruptive Seismic Velocity drops at the Piton de La Fournaise volcano: PREERUPTIVE Seismic Velocity DROPS
Geophysical Research Letters, 2015Co-Authors: Diane Rivet, Florent Brenguier, Frédéric CappaAbstract:The unexpected 2014 and 2015 Ontake (Japan) and Calbuco (Chile) eruptions proved that improving volcanic eruption prediction is still a great challenge. Decreases of Seismic velocities of the Piton de la Fournaise volcano inferred from Seismic noise correlations have been shown to precede eruptions. However, Seismic velocities are strongly influenced by rainfall and subsequent pore pressure perturbations. Here we increase the detection of precursory Seismic Velocity changes to an eruption by removing the effects of pore pressure changes. During 2011–2013, the volcano exhibits a low eruptive activity during which we observe Seismic Velocity variations well correlated with rainfall episodes. We estimated the transfer function between fluid pressure and Seismic Velocity changes. We use these results to correct Seismic Velocity change time series for pore pressure changes, due to rainfall and found a preeruptive Velocity drop (0.15%) associated with the 21 June 2014 eruption that was undetected before correction.
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Seismic Velocity changes, strain rate and non-volcanic tremors during the 2009–2010 slow slip event in Guerrero, Mexico
Geophysical Journal International, 2013Co-Authors: Diane Rivet, Michel Campillo, Mathilde Radiguet, Dimitri Zigone, Victor Cruz-atienza, Nikolai Shapiro, Vladimir Kostoglodov, Nathalie Cotte, Glenn Cougoulat, Andrea WalpersdorfAbstract:Seismic Velocity changes, strain rate and non-volcanic tremors during the S U M M A R Y We use ambient noise cross-correlations to monitor small but reliable changes in Seismic velocities and to analyse non-volcanic tremor (NVT) intensities during the slow slip event (SSE) that occurred in 2009 and 2010 in Guerrero. We test the sensitivity of the Seismic Velocity to strain variations in absence of strong motions. The 2009-2010 SSE presents a complex slip sequence with two subevents occurring in two different portions of the fault. From a Seismic array of 59 seismometers, installed in small antennas, we detect a Velocity drop with maximum amplitude at the time of the first subevent. We analyse the Velocity change at different period bands and observe that the Velocity perturbation associated with the SSE maximizes for periods longer than 12 s. Then a linearized inversion of the Velocity change measured at different period bands is applied in order to determine the depth of the portion of the crust affected by this perturbation. No Velocity change in the first 10 km is detected. Below, the Velocity perturbation increases with depth, affecting the middle and lower crust. Finally, we compute the transient deformation produced by the SSE in an elastic model using the slip evolution recovered from the inversion of continuous GPS. The comparison between the Velocity changes and the deformation suggests that the Velocity change is correlated with the strain rate rather than with the strain. This result is similar to what was observed during the 2006 SSE in the same region and suggests a non-linear behaviour of the crust. The Velocity changes can be interpreted together with other observables such as NVTs. During the 2009-2010 SSE we measure NVT activity using continuous Seismic records filtered between 2 and 8 Hz. We observe a correlation between Velocity changes (for period band greater than 14 s) and tremor activity whereas no correlation exists between Velocity changes and Seismic noise energy measured at long periods. These observations suggest that both Seismic Velocity change and NVT can be used as indication of transient deformation at depth.
Robert W. Clayton - One of the best experts on this subject based on the ideXlab platform.
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Mantle Heterogeneities and the SCEC Reference Three-Dimensional Seismic Velocity Model Version 3
Bulletin of the Seismological Society of America, 2003Co-Authors: Monica D. Kohler, Harold Magistrale, Robert W. ClaytonAbstract:We determine upper mantle Seismic Velocity heterogeneities below Southern California from the inversion of teleSeismic travel-time residuals. TeleSeismic P-wave arrival times are obtained from three temporary passive experiments and Southern California Seismic Network (SCSN) stations, producing good raypath coverage. The inversion is performed using a damped least-squares conjugate gradient method (LSQR). The inversion model element spacing is 20 km. Before the inversion, the effects of crustal Velocity heterogeneities represented by the Southern California Earthquake Center (SCEC) Seismic Velocity model version 2 are removed from the teleSeismic travel times. The P-wave inversion produces a variance reduction of 43%. S-wave velocities are determined from laboratory Vp/Vs ratios. The most prominent features imaged in the results are high P-wave velocities (+3%) in the uppermost mantle beneath the northern Los Angeles basin, and the previously reported tabular high-Velocity anomaly (+3%) to depths of 200 km beneath the Transverse Ranges, crosscutting the San Andreas fault. We incorporate the upper mantle Seismic Velocity heterogeneities into the SCEC Southern California reference Seismic Velocity model. The prior accounting for the crustal Velocity heterogeneity demonstrates the utility of the top-down method of the SCEC Seismic Velocity model development.
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the scec southern california reference three dimensional Seismic Velocity model version 2
Bulletin of the Seismological Society of America, 2000Co-Authors: Harold Magistrale, Robert W. Clayton, Steven M Day, Robert W GravesAbstract:We describe Version 2 of the three-dimensional (3D) Seismic Velocity model of southern California developed by the Southern California Earthquake Center and designed to serve as a reference model for multidisciplinary research activities in the area. The model consists of detailed, rule-based representations of the major southern California basins (Los Angeles basin, Ventura basin, San Gabriel Valley, San Fernando Valley, Chino basin, San Bernardino Valley, and the Salton Trough), embedded in a 3D crust over a variable depth Moho. Outside of the basins, the model crust is based on regional tomographic results. The model Moho is represented by a surface with the depths determined by the receiver function technique. Shallow basin sediment velocities are constrained by geotechnical data. The model is implemented in a computer code that generates any specified 3D mesh of Seismic Velocity and density values. This parameterization is convenient to store, transfer, and update as new information and verification results become available.
Harold Magistrale - One of the best experts on this subject based on the ideXlab platform.
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Mantle Heterogeneities and the SCEC Reference Three-Dimensional Seismic Velocity Model Version 3
Bulletin of the Seismological Society of America, 2003Co-Authors: Monica D. Kohler, Harold Magistrale, Robert W. ClaytonAbstract:We determine upper mantle Seismic Velocity heterogeneities below Southern California from the inversion of teleSeismic travel-time residuals. TeleSeismic P-wave arrival times are obtained from three temporary passive experiments and Southern California Seismic Network (SCSN) stations, producing good raypath coverage. The inversion is performed using a damped least-squares conjugate gradient method (LSQR). The inversion model element spacing is 20 km. Before the inversion, the effects of crustal Velocity heterogeneities represented by the Southern California Earthquake Center (SCEC) Seismic Velocity model version 2 are removed from the teleSeismic travel times. The P-wave inversion produces a variance reduction of 43%. S-wave velocities are determined from laboratory Vp/Vs ratios. The most prominent features imaged in the results are high P-wave velocities (+3%) in the uppermost mantle beneath the northern Los Angeles basin, and the previously reported tabular high-Velocity anomaly (+3%) to depths of 200 km beneath the Transverse Ranges, crosscutting the San Andreas fault. We incorporate the upper mantle Seismic Velocity heterogeneities into the SCEC Southern California reference Seismic Velocity model. The prior accounting for the crustal Velocity heterogeneity demonstrates the utility of the top-down method of the SCEC Seismic Velocity model development.
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the scec southern california reference three dimensional Seismic Velocity model version 2
Bulletin of the Seismological Society of America, 2000Co-Authors: Harold Magistrale, Robert W. Clayton, Steven M Day, Robert W GravesAbstract:We describe Version 2 of the three-dimensional (3D) Seismic Velocity model of southern California developed by the Southern California Earthquake Center and designed to serve as a reference model for multidisciplinary research activities in the area. The model consists of detailed, rule-based representations of the major southern California basins (Los Angeles basin, Ventura basin, San Gabriel Valley, San Fernando Valley, Chino basin, San Bernardino Valley, and the Salton Trough), embedded in a 3D crust over a variable depth Moho. Outside of the basins, the model crust is based on regional tomographic results. The model Moho is represented by a surface with the depths determined by the receiver function technique. Shallow basin sediment velocities are constrained by geotechnical data. The model is implemented in a computer code that generates any specified 3D mesh of Seismic Velocity and density values. This parameterization is convenient to store, transfer, and update as new information and verification results become available.
